We present the discovery of a hot Jupiter transiting an F star in a close visual (0[" over .]3 sky projected angular separation) binary system. The dilution of the host star's light by the nearly equal magnitude stellar companion (~0.5 mag fainter) significantly affects the derived planetary parameters, and if left uncorrected, leads to an underestimate of the radius and mass of the planet by 10% and 60%, respectively. Other published exoplanets, which have not been observed with high-resolution imaging, could similarly have unresolved stellar companions and thus have incorrectly derived planetary parameters. Kepler-14b (KOI-98) has a period of P = 6.790 days and, correcting for the dilution, has a mass of M[subscript p] = 8.40[superscript +0.35] [subscript – 0.34] M [subscript J] and a radius of R[subscript p] = 1.136[superscript +0.073] [subscript – 0.054] R [subscript J], yielding a mean density of ρ [subscript p] = 7.1 ± 1.1 g cm[superscript –3].